BIOL 2903 Lecture 5: Week 5
14 Feb 2017
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Document Summary
Bedrock covered by thick clay & silt deposits from tyrrell sea. Flat, discontinuous permafrost + impervious deposits = poor drainage = lots of water. Cold + wet = ideal conditions for sphagnum moss: sphagnum moss creates peatlands. Peatlands = dominant habitats in hbl: peat > 45cm thick & wet = muskeg. 1 of largest expanses of continuous muskeg in world. Stunted black spruce & tamarack characterize hbl muskeg. Trees grow taller & form continuous forest in some sites. Bogs & fens = 2 major types of peatland: bog receive water & nutrients only by rainfall; dominated by sphagnum moss, fens receive nutrients from flowing groundwater, such as streams & often sedge- dominated. Sedges (such as carex lasiocarpa, c. limosa, or c. chordorhiza) colonize & grow out into water. Sphagnum begins spreading & dominating: modifies environment making it: Acidic, nutrient poor, oxygen deprived: provides its own water b/c it"s built like a sponge.
